Steatite bodies are used primarily as high frequency insulating bodies in the electronic and electronic and electrical appliance industries and are characterized by their high dielectric strength over wide temperature ranges, low power loss in the high frequency field, a water absorption of less than one percent and a high impact or mechanical resistance.
The common practice in the manufacture of steatite products consists in mixing silica-rich magnesium silicate rocks such as clinoenstatite crystals (talc) with small amounts of clay and a ceramic flux.
Typical steatite compositions presently available analyze as follows:
__________________________________________________________________________ SiO.sub.2 MgO Al.sub.2 O.sub.3 K.sub.2 O Fe.sub.2 O.sub.3 TiO.sub.2 CaO Na.sub.2 O BaO % % % % % % % % % __________________________________________________________________________ (a) 64.74 28.24 4.45 1.03 0.83 0.03 0.25 0.43 -- (b) 61.7 29.23 2.55 0.05 1.22 0.03 0.05 0.11 5.16% __________________________________________________________________________
It will be seen that contrary to (a), (b) contains alkaline earth oxide flux (BaO) which improves dielectric properties. It will also be seen that the iron oxide content (Fe.sub.2 O.sub.3) is relatively low in these compositions.
It is also known that serpentine, particularly chrysotile asbestos contains the two most important constituents of steatite, namely, magnesiun oxide and silica: Appreciating the enormous amount of chrysotile asbestos tailings and residues present near every asbestos mine in the world appear highly desirable if a procedure could be found to use these tailings and residues in the manufacture of steatite compositions whereby a substantial reduction in cost would be achieved while at the same time creating a new use of these tailings and residues for which only limited use has been found. It will also be appreciated that asbestos fibers represent only about 5% by weight of the mined asbestos rock and thus the cost of the tailings and residues is already included in the selling price of all asbestos fibers.